Glycoproteins and glycolipids have been implicated in cell-cell interactions, cellular growth regulation and differentiation, as well as tumour antigens. Currently, we are investigating the distribution and partition of glycoproteins and glycolipids in the plasma and intracellular membranes of normal and SV40 virus-transformed WF-38 fibroblasts. The lectins concanavalin A(Con A), Ricinus communis agglutin (RCA), Wheat Germ Agglutinin (WGA) and Ulex europeus agglutinin (UEA) are used as probes. It is our intention to characterize glycoproteins and glycolipids based on a ) their partition behaviour during freeze-fracture; b) their resistance or susceptibility to selected enzymatic degradations and c) their presence after treatment of cell cultures with specific inhibitors such as tunicamycin.